Competing hydrogen evolution reaction (HER) and sluggish multi-electron/proton-involved steps are the major obstacles to improving the efficiency and selectivity of electrochemical nitrate reduction to ammonia (eNO₃RR). Herein, we modified Co₃O₄ nanoparticles with doped rare-earth La atoms and carboxylic (COO⁻)-based organic ligands. The COO⁻ groups efficiently reduce the water activity around the active sites by forming hydrogen bonds, thus controlling proton accessibility and regulating the adsorption selectivity between nitrate ions and protons. Simultaneously, introducing oxygen vacancies through La doping establishes active sites with a strong affinity for nitrate ions and an electron-rich local environment conducive to eNO₃RR. The electrocatalyst exhibits superior activity and selectivity with an ammonia Faradaic efficiency of up to 99.41% and a yield rate of 5.62 mg h⁻¹ mg_cat⁻¹ at −0.3 V vs. reversible hydrogen electrode (RHE). Notably, the catalyst maintains over 90% Faradaic efficiency for NH₃ production across a broad potential range of 400 mV, surpassing most recently reported eNO₃RR electrocatalysts.

竞争性析氢反应（HER）和缓慢的多电子/质子参与步骤是提高电化学硝酸盐还原氨（eNO ₃ RR）效率和选择性的主要障碍。在此，我们用掺杂稀土La原子和羧基（COO ⁻ ）有机配体修饰了Co ₃ O ₄ 纳米颗粒。 COO ⁻ 基团通过形成氢键有效降低活性位点周围的水活度，从而控制质子的可达性并调节硝酸根离子和质子之间的吸附选择性。同时，通过La掺杂引入氧空位建立了对硝酸根离子具有强亲和力的活性位点和有利于eNO ₃ RR的富电子局部环境。该电催化剂表现出优异的活性和选择性，在-0.3时氨法拉第效率高达99.41%，产率为5.62 mg·h ⁻¹ mg _cat ⁻¹ V 与可逆氢电极 (RHE)。值得注意的是，该催化剂在 400 mV 的宽电位范围内保持超过 90% 的 NH ₃ 生产法拉第效率，超过了最近报道的 eNO ₃ RR 电催化剂。